<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<style>
    .container li .i{
        background-color: red;
    }
</style>
<div class="container">
    <ul>
        <li>aaadfdf</li>
        <li class="i">aaadfdf</li>
        <li>aaadfdf</li>
    </ul>
</div>
</body>
</html>